The History of RFID Technology – Looking Back at Its First Patents

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The 1st patent (US-based) that used the term RFID (radio frequency identification) was granted in the year 1983 by an American inventor Charles Walton. Although many individuals actually contributed and assisted to the invention of RFID technology, Charles Walton was awarded 10 patents for a number of RFID related devices. His 1st RFID patent granted began in seventies with the design for a “Portable radio frequency emitting identifier”. The abstract of the patent stated the following, ‘An automatic identification system wherein a portable identifier, preferably shaped like a credit card, incorporates an oscillator and encoder so as to generate a programmable pulse position-modulated signal in the radio frequency range for identification of the user. The identifier can be made to generate the identification signal constantly or can be made for stimulated transmission responsive to an interrogation signal. The identification signal can be preset or can be programmable by use of a programmable memory.’ The entire ‘Portable radio frequency emitting identifier’ patent can be viewed here.

Some state that Mario Cardullo’s device, filed on May 21, 1970 and issued in 1973, was the first true ancestor of modern RFID, as it was a passive radio transponder with memory and covers the use of RF, sound and light as transmission media. The patent abstract of Mario Carullo’s transponder apparatus and system states the following: ‘A novel transponder apparatus and system is disclosed, the system being of the general type wherein a base station transmits an “interrogation” signal to a remote transponder, the transponder responding with an “answerback” transmission. The transponder includes a changeable or writable memory, and means responsive to the transmitted interrogation signal for processing the signal and for selectively writing data into or reading data out from the memory. The transponder then transmits an answerback signal from the data read-out from its internal memory, which signal may be interpreted at the base station. In the preferred inventive embodiment, the transponder generates its own operating power from the transmitted interrogation signal, such that the transponder apparatus is self-contained.’ The entire ‘ transponder apparatus and system’ patent can be seen here.

In 1945 Léon Theremin invented an espionage tool for the Soviet Union which retransmitted incident radio waves with audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, which modulated the reflected radio frequency. Even though this device was a covert listening device, not an identification tag, it is considered to be a predecessor of RFID technology, because it was likewise passive, being energized and activated by waves from an outside source. (1)

It is also said that an early demonstration of reflected power (modulated backscatter) RFID tags, both passive and semi-passive, was performed by Steven Depp, Alfred Koelle, and Robert Freyman at the Los Alamos National Laboratory in 1973. (2) The portable system operated at 915 MHz and used 12-bit tags. This technique is used by the majority of today’s UHFID and microwave RFID tags.

Based on the various patents and demonstrations around RFID-based technology, it is safe to assume that the early 1970s is when RFID started to take form.